1. Field of the Invention
The present invention pertains to an apparatus and process for liquid purification or separation, and also for liquid transfer. Although the invention can be used for liquid-liquid separations, the present invention is most useful in the purification of liquids by filtering small solid particulates from the liquid. The invention utilizes a moveable medium for the filtration process. In addition to the separation of the components of a mixture, the present invention enables one to simultaneously separate a liquid from a mixture while transferring the separated liquid to another container without risk of spillage or contamination of the separated liquid.
2. Description of the Prior Art
U.S. Pat. No. 3,955,423 (hereinafter the '423 patent) is the first of two U.S. patents which the applicant considers to be the closest art with respect to the present invention. The subject matter of the '423 patent involves a device " . . . for isolating a liquid sample from a specimen container . . . ." The '423 patent utilizes an elongated cylindrical collection tube which terminates, on its lowermost end, with a filter means. The cylindrical collection tube slides in sealed contact with the inner surface of a specimen container which is holding a liquid sample. On the uppermost end of the cylindrical collection tube is an air escape notch or opening and still further above, a collection cup serves as a protective cap for the uppermost end of the collection tube. Although the device of the '423 patent is closely related to the device of the present invention, several important distinctions between the '423 patent teachings and the device and process of the present invention can be made, as follows:
(1) In the '423 patent, filtration cannot be accomplished while the apparatus is in an inverted position, without creating spillage and/or operability problems; and PA1 (2) and device of the '423 patent requires that the filtration step take place while the apparatus is in an upright position (i.e. the specimen tube remains lowermost). after which the apparatus is inverted for the transfer step. PA1 (1) In the '477 device, the collection vial is completely unconnected to the plunger, whereas in the instant invention there is contact between the plunger and the collection vial; PA1 (2) the device of the '477 patent is not substantially encased, resulting in the potential for spillage, release of dangerous volatile components, and sample contamination, while, in contrast, the device of the present invention provides for substantial encasement of the components being handled, reducing the risk of spillage, release of dangerous volatile components, and sample contamination. while permitting the escape of displaced gas; and PA1 (3) the device of the '477 patent requires alignment of the receiving vessel (19) and the flexible tubing (15). This alignment can be disturbed by the movement of plunger tube (12), whereas the device of the present invention has no similar critical alignment.
In contrast, the apparatus and process of the present invention solves problems associated with the device taught in the '423 patent. First, as is discussed in detail below, the device and process of the instant invention permit both filtration and transfer to be carried out while the device is "inverted", without permitting either spillage, contamination or operability problems. Secondly, the device and process of the instant invention permit the escape of displaced gas (i.e. air) during the filtration process, without permitting spillage of filtered liquid. Third, the device and process of the instant invention permit filtration while substantially eliminating potential contamination due to exposure to the atmosphere. The solution to these three problems permits an easier filtration and transfer of liquid without risk of spillage or contamination. Furthermore, the device and process of the present invention are significantly less complicated than both the device and process taught in the '423 patent.
Also relevant to the present invention is U.S. Pat. No. 3,481,477 (hereinafter the '477 patent). The '477 patent teaches an apparatus for filtering/separating liquids. The apparatus has an outer tubular member within which slides a hollow plunger which has a sealed fit with the interior surface of the tubular member. The hollow plunger has a filter therein. After the liquid being filtered proceeds a very short distance into the plunger, it is immediately forced into a tube of small diameter which is concentrically arranged within the plunger. The tube directs the filtered liquid up and out of the other end (i.e. the upper end) of the plunger and then down and into a separate vial. The subject matter of the '477 patent differs from the subject matter of the present invention in many ways, several of which are described as follows:
Applicant is aware of still further prior art U.S. patents including the following: U.S. Pat. Nos. 4,300,404; 4,210,623; and 3,969,250. Although these patents are also related to the present invention, applicant contends that they are not closely related enough to deserve any detailed discussion regarding the patentability of the present invention. None of the prior art referred to herein teaches simultaneous filtration and transfer utilizing an inverted device.
In summary, although each of the advantages of the present invention over the technology described in the prior art is important, the combination of advantages of the present invention, along with its simplicity of design and ease of manufacture, make it especially advantageous for the separation of components from mixtures.